Enhancing salinity tolerance in potato (Solanum tuberosum L.) using foliar-applied branched-chain amino acids

Salinity stress is a major constraint to potato production in sandy soils under arid environments. This study evaluated the effectiveness of foliar-applied branched-chain amino acids (BCAAs)-valine, leucine, and isoleucine-applied individually or in combinations to enhance salinity tolerance of potato (Solanum tuberosum L. cv. Kara) during the 2023 and 2024 growing seasons in Wadi El Natrun. A split-plot randomized complete block design with three replicates was used, where three salinity levels (0, 1500, and 3000 ppm NaCl) were assigned to main plots, while eight BCAA treatments were allocated to subplots: control (water spray), valine (2 g L⁻¹), leucine (2 g L⁻¹), isoleucine (2 g L⁻¹), valine + leucine (1 g L⁻¹ each), valine + isoleucine (1 g L⁻¹ each), leucine + isoleucine (1 g L⁻¹ each), and valine + leucine + isoleucine (0.75 g L⁻¹ each). Salinity significantly reduced vegetative growth, tuber number, and total yield, particularly at 3000 ppm NaCl. Foliar BCAA application mitigated these adverse effects. Under moderate salinity, isoleucine and dual combinations increased yield up to 45.22 tons ha⁻¹ versus 29.35 tons ha⁻¹ in untreated plants. Under severe salinity, the combined treatment (V + L+I) produced the highest yield (42.05 tons ha⁻¹). Enhanced proline accumulation, protein content, and antioxidant enzyme activity indicated improved stress tolerance. BCAAs represent an effective strategy for sustaining potato productivity in salt-affected soils.